PPolySim OS

BJT Transistor Bias

Before a transistor can amplify, it must be biased. Set the resistor network and watch the operating point land on the load line — in the active region, or clipped into saturation.

BJT Transistor BiasLive

Controls

Presets

Voltage-divider bias sets a transistor's operating point (Q-point) stably against variations in β. The base voltage fixes the emitter current, and the collector-emitter voltage falls on the DC load line. For a clean amplifier, the Q-point should sit near the middle of the active region.

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Data Inspector

Collector current Ic2.52 mA
Vce8.22 V
Base voltage2.11 V
Regionactive

Governing equation

Reading this result: The Q-point sits near mid-load-line — the sweet spot for a linear amplifier, giving the largest symmetric output swing.

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How it works

Voltage-divider bias fixes a bipolar transistor's operating point (Q-point) so it stays stable despite variations in current gain β. The base network sets the emitter current, and the collector-emitter voltage falls on the DC load line. A well-designed amplifier places the Q-point near mid-line, giving maximum symmetric swing before clipping.

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Frequently asked questions

Is this BJT bias Q-point calculator tool really free?
Yes. BJT Transistor Bias runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.